Introduction

The genus Scolelepis was revised by Maciolek (1987) who established two subgenera, Scolelepis and Parascolelepis, based on the morphology of the hooded hooks. Subgenus ScolelepisDe Blainville, 1828 included species having uni- to tridentate hooks with a falcate or straight shaft, while subgenus ParascolelepisMaciolek, 1987 included species having multidentate hooks with a curved shaft. Maciolek (1987) also described three new species from the eastern coast of the United States. After that, Imajima (1992) described six new Scolelepis species from Japan, Eibye-Jacobsen (1997) described S. (Scolelepis) laciniata from Thailand, and Eibye-Jacobsen and Soares (2000) described S. (S.)vazaha from Madagascar. Currently, 56 Scolelepis species are recognized, including 45 of the subgenus Scolelepis, and 11 species of Parascolelepis.

Few Scolelepis species have been described from the Grand Caribbean Region:Nerine minutaTreadwell, 1939 from Texas, and Nerinides goodbodyiJones, 1962 from Jamaica. However, these species were synonymized with Scolelepis squamataMüller, 1806 by Pettibone (1963) and she also included other species such as Nerine agilisVerrill, 1873 from New Jersey, Lumbricus cirratulusDella Chiaje, 1828 from the Mediterranean, Malacoceros longirostris De Quatrefages, 1843 from France, Nerine heteropodaWebster, 1879 from Virginia, Spio acutaTreadwell, 1914 from California, and Nerine capensisMcIntosh, 1925 from South Africa, into synonymy with Scolelepis squamataMüller, 1806. Thereafter, Foster (1971) described one species from the Gulf of Mexico belonging to Parascolelepis, and recorded S. (S.) squamata (Müller, 1806),which was originally described from Denmark.

In this work, I review type and non-type material of certain species previously synonymized with S. (S.)squamata(Müller, 1806), as well as other species from the Grand Caribbean Region, and distinguish between the described species. This results in the reinstatement of four species and the description of two new species, and an identification key to Scolelepis species from the Grand Caribbean region is provided.

Material and methods

The material was collected off the Mexican coast in the states Tamaulipas, Tabasco, Campeche, Yucatan, and Quintana Roo. Specimens were fixed in 10% formaldehyde and later preserved in 70% ethanol. Additional material was collected in the oil platform area in the southern Gulf of Mexico during one oceanographic cruise: Dinamo II (Nov. 1990). Information about these cruises is provided by Granados Barba and Solis Weiss (1998). Drawings were made with a camera lucida. Specimens were measured with a millimetre rule; width includes parapodia but not chaetae.

The material has been deposited in several insti-tutions: the Reference Collection of El Colegio de la Frontera Sur, Unidad Chetumal (ECOSUR), Chetumal, Mexico; Los Angeles County Museum of Natural History, Allan Hancock Foundation (LACMNH-AHF), Los Angeles, USA; United States National Museum of Natural History, Smithsonian Institution (USNM), Washington, D.C, USA; Rosenstiel School of Marine and Atmospheric Sciences, The Invertebrate Museum, University of Miami (UMML), Miami, USA; American Museum of Natural History, New York, U.S.A. (AMNH); Colección de Poliquetos, Laboratorio de Ecología Costera (Poliquetos) (LECyP-ICML-UNAM), México. In the following, the number of specimens in a sample is given in parentheses after the museum abbreviation.

For scanning electron microscopy (SEM), specimens were critical point dried using carbon dioxide, covered with gold-palladium, and then viewed with a Topcon SM-510 in El Colegio de la Frontera Sur, Tapachula, Chiapas.

Branchiae present from chaetiger 2 to end of body (absent on last chaetiger of body), with thick, glandular, subtriangular tips (Fig. 1E); almost completely fused to notopodial postchaetal lamellae (Fig. 1E, J); each branchia with band of cilia along inner edge; each segment also with dorsal, transverse band of cilia, not continuous with ciliation of branchiae (Fig. 1A).

Neurochaetae arranged in two rows on anterior chaetigers. Neuropodia of anterior chaetigers with capillaries only, those of anterior row broadest, moderately granulated, weakly bilimbate (Fig. 1K), shorter than those of posterior row. Neuropodial hooded hooks from chaetiger 43, up to 9 present per neuropodium, accompanied with two long chaetae above and two short chaetae below the hooks. Hooded hooks with bluntly rounded main fang surmounted by one or two smaller accessory teeth placed side by side, with long, slightlycurved shaft (Fig. 1L). Sabre chaetae absent.

Notopodial capillary chaetae similar in morphology to those of neuropodia although more elongate, arranged in two rows, those of posterior row longest (Fig. 1M). Notopodial hooded hooks from chaetiger 85-92, up to six present per notopodium, accompanied with four long chaetae above and two short chaetae below the hooks. Hooded hooks with bluntly rounded main fang surmounted by one or two smaller accessory teeth placed side by side; with long, almost straight shaft (Fig. 1N-P).

Foster (1971) made special reference to the variation of the dentition of the hooded hooks and stated that there was some confusion and inconsistency regarding the presence or absence of notopodial hooks in the species synonymized with S. squamata by Pettibone (1963). Light (1977, 1978) observed the same variation and also commented that the presence of a notch in middle and posterior neuropodial lamellae was quite variable among specimens from San Francisco and that this feature shows a continuous distribution within a single sample. On the basis of adult morphology, Light (1977) could not distinguish between the paratype Spio acuta from San Diego, the holotype of Nerine minuta from Texas, specimens identified as Nerine agilis from the northeast coast of North America, and specimens identified as S. squamata from both coasts of North America, The Netherlands, and Italy. Maciolek (1987) examined specimens from the east coast of North America, mostly small ones, including some postlarval or juvenile forms. All her specimens were consistent in having bilobed neuropodial lamellae and bi- or tridentate hooks, and all the material was identical with the syntypes of S. agilis (Verrill). Moreover, she studied some specimens identified as Nerine cirratulus from Italy and The Netherlands. The Italian specimens (Naples) had some differences in the shape of the bilobed neuropodial lamella of middle chaetigers and their unidentate hooded hooks had some indication of having apical teeth, while all the Dutch specimens had similar bilobed lamella in middle chaetigers and bi- or tridentate hooks. Also, Blake (1996) supported the synonymies, commenting that the presence of a thickened basal palpal sheath on both Atlantic and Pacific specimens of S. squamata was identical and that this structure not had been reported for any species of Scolelepissensu stricto.

However, I have revised the holotype of Nerine minuta, the holotype and paratypes of Nerinides goodbodyi, the syntypes of Nerine agilis, the paratypes of Spio acuta, specimens identified as S. squamata from England and the Gulf of Mexico, and several important differences were found and are employed here to remove the four first species from synonymy with S. squamata. The differences between these species can be seen in the remarks on each species, in the key and in Table 1.

Branchiae present from chaetiger 2 to end of fragment, elongate, tapered, longest on anterior and middle part of body, almost completely fused to notopodial lamella in anterior chaetigers (Fig. 2D-F), with free, pointed tips; branchiae of posterior chaetigers fused basally to lamellae.

Branchiae present from chaetiger 2 to end of body (absent on last chaetiger of body), tapered are elongate, longest on anterior and middle part of body, almost fused to notopodial postchaetal lamellae (Fig. 3D, E); branchiae of posterior chaetigers fused basally to lamellae (Fig. 3I, J); tips of branchiae free. Each branchia with band of cilia along inner edge (Fig. 3I, J).

Neurochaetae arranged in two rows on anterior chaetigers. Neuropodia of anterior chaetigers with capillaries only, those of anterior row broadest, heavily granulated, weakly bilimbate, shorter than those of posterior row (Fig. 3K). Neuropodial hooded hooks from chaetiger 27-30, up to 10 present per neuropodium, accompanied by up to threeslender chaetae above and two short chaetae below the hooks. Hooded hooks with two smaller accessory teeth surmounting large main tooth (Fig. 3L); posterior hooks with bidentate appearance (Fig. 3L); with long, curved shaft. Sabre chaetae absent.

Notopodial capillary chaetae similar in morphology to those of neuropodia although more elongate, arranged in two rows, those of posterior row longest. Notopodial hooded hooks from chaetiger 62-72, up to four present per notopodium, accompanied by four long chaetae above and two short chaetae below the hooks. Hooded hooks tridentate, with long, straight shaft (Fig. 3N).

Remarks. Hartman (1951) reported Nerine agilis from the Gulf of Mexico mentioning the presence of notopodial and neuropodial hooks; later, Hartman (1956) transfered this same species to Nerinides because it lacks hooded hooks in the notopodia. Nerine agilis was synonymized with S. squamata by Pettibone (1963), S. squamata being characterized by the presence or absence of notopodial hooks (Foster, 1971; Light, 1978; Blake, 1996). However, the specimens of S. (S.) agilis from New Jersey have notopodial hooks, as mentioned by Maciolek (1987). Scolelepis (S.) agilis resembles S. squamata in having low lateral wings, a long peristomium, bilobed anterior notopodial lamellae, and notopodial hooded hooks. However, Scolelepis (S.) agilis differs from S. (S.) squamata in that the former has elongated, tapered branchiae, oval posterior notopodial lamellae with an elongated pointed tip and the lower corners of ventral lamellae in posterior chaetigers triangular, dorsal folds and crests, and only tridentate hooded hooks. While S. (S.) squamata has branchiae with thick, glandular, subtriangular tips, and the posterior notopodial lamellae areentirewith rounded lower corners, dorsal ridges are present, and hooded hooks are uni, bi-, or tridentate.

Nerine heteropodaWebster, 1879 was synonymized withNerine agilis by Hartman (1945), and with S. squamata by Pettibone (1963). However,N. heteropodashould be revised, even though Nerine heteropoda and S. agilis do not seem to show any morphological differences.

Branchiae present from chaetiger 2 to end of body (absent on last chaetiger of body); branchiae long, gently tapered, longest on anterior and middle part of body (Fig. 4D); almost fused to notopodial postchaetal lamellae in anterior chaetigers (Fig. 4E-H); branchiae of posterior chaetigers fused basally to lamellae (Fig. 4K); free tips of branchiae tapered; each branchia with band of cilia along inner edge. Mid-region of branchiae with highly glandular cell margin in chaetigers 14-38 (Fig. 4I-K).

Neurochaetae arranged in two rows on anterior chaetigers. Neuropodia of anterior chaetigers with capillaries only, those of anterior row moderately granulated, nearly straight, bilimbate and short (Fig. 4M); chaetae of posterior row similar to anterior row, but without granulation and longer (Fig. 4M). Neuropodial hooded hooks from chaetiger 25, numbering seven-nine per neuropodium, accompanied by two-three long chaetae above and two short chaetae below the hooks. Hooded hookswith one or two small apical teeth surmounting large main tooth (Fig. 4N); with long, curved shaft, (Fig. 4N). Sabre chaetae absent.

Notochaetae of chaetiger 1 arranged in two rows, those of anterior row abruptly curved and very broad (Fig. 4O), in posterior row nearly straight and thin (Fig. 4O). The other notopodial capillary chaetae similar in morphology to those of neuropodia, although more elongate, arranged in two rows, those of posterior row longest (Fig. 4P). Notopodial hooded hooks absent.

Pygidium with ventral cushion.

ariability. Paratypes6.5-13 mm long, 0.7-1 mm wide, with 38-55 chaetigers. Several ovigerous. Body wide anteriorly, becoming distinctly narrower, almost cylindrical in cross section from around chaetiger 20-24. Palps extending up to chaetigers 14-22. Mid-region of branchiae with highly glandular cell margin from chaetigers 13-19 (in some paratypes from chaetiger 10-13). All paratypes with low dorsal folds starting from chaetiger 3, thereafter becoming low dorsal crests in middle and posterior segments up to the end of the body.All specimens with neuropodial lamellae anteriorly rounded, with notch from chaetiger 18, in only one specimen from chaetiger 19; lamellae becoming distinctly bilobed by chaetiger 19, in only one specimen by chaetiger 20. Neuropodial hooded hooks from chaetigers 24-26, numbering one-nine per fascicle.Hooded hooks with one or two apical teeth.

Remarks. Scolelepisgoodbodyin. comb. was synonymized with Scolelepis squamata by Pettibone (1963); however, S.goodbodyi differs from S. (S.)squamata in that the former has oval anterior notopodial lamellae with an elongated pointed tip, oval posterior notopodial lamellae with a lower cornerpointed, notopodial hooded hooks absent. Scolelepisgoodbodyi further differs from all species in having the mid-region of branchiae with highly glandular cell margin, and notochaetae of chaetiger 1 of two types: 1) abruptly curved and very broad, and 2) nearly straight and thin. The main differences between Scolelepisgoodbodyin. comb. and other species from the Grand Caribbean Region can be seen in the key and Table 1.

Branchiae present from chaetiger 2 to end of body (absent on last chaetiger of body); branchiae tapered, elongate, longest on anterior and middle part of body; partially fused to notopodial postchaetal lamellae (Fig. 5B); branchiae of posterior chaetigers fused basally to lamellae; each branchia with band of cilia along inner and outer edge.

Neurochaetae arranged in two rows on anterior chaetigers. Neuropodia of anterior chaetigers with capillaries only, those of anterior row broadest, limbate, heavily granulated, shorter than those of posterior row. Neuropodial hooded hooks from chaetiger 27, numbering one-seven per fascicle, accompanied by one or two slender, striated capillaries above and three or four stout, striated capillaries below the hooks;posterior hooks accompanied by two small, broad, limbate, finely punctuated chaetae (Fig. 5I). Hooded hooks with 2 small apical teeth surmounting large main tooth; with long, curved shaft (Fig. 5J, H).

Notopodial capillary chaetae similar in morphology to those of neuropodia although more elongate, arranged in two rows, those of posterior row longest. Notopodial hooded hooks present from chaetiger 83, numbering 1 per fascicle. Hooks with pointed main fang surmounted by two small apical teeth (Fig. 5J, H). Sabre chaetae absent.

Variability. Paratypes 5.4-26 mm long, 0.5-2.3 mm wide, with 48-101 chaetigers.Palps long (Fig. 6A), extending posteriorly to chaetigers 16-18; ciliation consists of two longitudinal bands of transverse rows of cilia. Palpswith basal sheath (Fig. 6B) (palps lost in holotype and many specimens).Eyes arranged in a transverse row or in trapezoid; lateral eyes kidney-shaped and inner ones rounded; there are big reddishspots above the eyes. Some specimens with inflated caruncle, and narrow curved semicircular nuchal organs surrounding posterior margin of prostomium (Fig. 6A). Each branchia with a ciliated band along the edges (Fig. 6C, D); each segment also with a dorsal, transverse band of cilia, continuous with branchial ciliation on chaetigers 3 to 28; thereafter ciliary bands on low dorsal crests to end the body (Fig. 6D). All specimens with neuropodial lamellae rounded on anterior chaetigers (Fig. 6E), developing notch around chaetiger 21-25 (usually one or two lamellae with notch). Notch becoming deeper, dividing lamellae into separate lobes around chaetigers 22-29 (usually two-four bilobed lamellae), on posterior chaetigers dorsal neuropodial lamellae square with triangular dorsal projection (Fig. 6F).Neuropodial hooded hooks present from chaetigers 13-29(usually chaetiger26), numbering one-nineper fascicle. Notopodial hooded hooks from chaetiger 40-83, two per fascicle. All specimens have hooks with large main fang surmounted by two small apical teeth.

Remarks. Scolelepis (S.) lighti n. sp. is most similar to S. squamata. It differs in the form of the anterior and middle notopodial lamellae, the shape of branchiae, and having only tridentate hooded hooks. Differences compared to other, similar species can be seen in the key and in Table 1.

Distribution.- Gulf of Mexico: Tamaulipas, Tabasco, Quintana Roo.

Etymology.This species is dedicated to Dr. William J. Light, in recognition of his research and publications on spionids.

Branchiae present from chaetiger 2 to end of body (absent on last chaetiger of body); branchiae elongate oval, longest on anterior and middle part of body; anterior and middle branchiae narrow abruptly at the apices (Fig. 7D-G); branchiae partially fused to notopodial postchaetal lamellae (Fig. 7D-G); branchiae of posterior chaetigers fused basally to lamellae (Fig. 7I-K); each branchia with band of cilia along inner edge.

Neurochaetae arranged in two rows on anterior chaetigers. Neuropodia of anterior chaetigers with capillaries only, those of anterior row broadest, moderately granulated, limbate, shorter than those of posterior row. Neuropodial hooded hooks from chaetiger35, up to seven per neuropodium, accompanied with two long chaetae above and two short chaetae below the hooks. Hooded hooks tridentate(Fig. 7O). Sabre chaetae absent.

Anterior notochaetae all capillaries, arranged in two rows. Notochaetae of chaetiger 1 thin and shorter than on other chaetigers; in chaetigers 2-10, those of anterior row slightly broader, heavily granulated, weakly limbated, shorter (Fig. 7M); posterior row without granulation and up to four capillaries extremely long in superior position of fascicle (Fig. 7N).

Remarks. Scolelepis minuta was synonymized with Nerine agilis by Hartman (1951, 1956), and with S. squamata by Pettibone (1963). It differs from both these species in the following characters: a short peristomium, oval anterior notopodial lamellae with an elongated pointed tip, and notopodial hooks absent. One character than can be used to separate them is the shape of branchiae: in S. minuta the branchiae narrow abruptly at the apices, whereas in S. squamata they have thick, glandular, subtriangular tips, and in S. agilisthey are elongated, tapered. Differences compared to other, similar species can be seen in the key and Table 1.

Branchiae present from chaetiger 2 to end of body (absent on last chaetiger of body), branchiae tapered elongate, longest on anterior and middle part of body (Fig. 9B); partially fused to notopodial postchaetal lamellae (Fig. 8B-D); branchiae of posterior chaetigers fused basally to lamellae (Fig. 8E-G); free tips of branchiae and lamellae tapered, elongate. Each branchia with band of cilia along inner edge (Fig. 9D).

Neurochaetae arranged in two rows on anterior chaetigers. Neuropodia of anterior chaetiger with capillaries only, those of anterior row broadest, heavily granulated, weakly bilimbate, shorter than those of posterior row. Neuropodial hooded hooks from chaetiger 25, up to 10 present per neuropodium, accompanied with one or two slender chaetae above and two short chaetae below the hooks. Hooded hooks with bluntly rounded main fang surmounted by one or two smaller accessory teeth placed side by side (Fig. 8H, K); with long, slightlycurved shaft (Fig. 8K). Sabre chaetae absent.

Notopodial capillary chaetae similar in morphology to those of neuropodia although more elongate, arranged in two rows, those of posterior row longest. Notopodial hooded hooks from chaetiger 56, up to three per notopodium, accompanied with four long chaetae above and two short chaetae below the hooks. Hooded hooks uni-, bi-, or tridentate; and with a long striate principal hood (Fig. 8H, I, K); with long, almost straight shaft.

Variability. Paratypes 16.3-19 mm long, 0.8-2.0 mm wide, 69-71chaetigers.All specimens without peristomial wings; peristomium is not free from the prostomium(Fig. 9A, B). Palps extending to chaetigers 22-23, each ciliary band as transverse rows of cilia (Fig. 9C). Each row in median band up to 50 µm long; ciliary groove absent. Some specimens with two pairs of rounded eyes arranged in a transverse row;one specimen with three rounded eyes (UMML-000), and other specimen with kidney-shaped lateral eyes and rounded inner eyes (UMML-000). All specimens with anterior notopodial lamellae bilobed, upper lobe subtriangular elongate and lower lobe broad rounded (Fig. 9D). Each segment with a dorsal, transversal band of cilia, not continued from branchial ciliation (Fig. 9B). All specimens with low dorsal crest from chaetigers 22-28 to the end of the body, one specimen with low folds alternating in anterior segments (chaetigers 3-27), one ridge per segment, thereafter becoming moderate dorsal crests (Fig. 9F) (UMML-000).

Remarks. Scolelepis (Scolelepis) vossae is most similar to S. (S.)squamata and S. (S.) goodbodyi. It differs from those species and all other species of the genus in having the peristomium completely fused with the prostomium and lacking of lateral peristomial wings.

Distribution. Florida.

Etymology. This species is dedicated to Dr. Nancy Voss for her important research activities in the Rosenstiel School of Marine and Atmospheric Sciences, her tireless management of The Invertebrate Museum, University of Miami (UMML), Miami, USA, and for her warm support to our research program on Grand Caribbean Region polychaetes.

Variability. The description above is based on a complete specimen. Other specimens 4.2-10 mm long, 0.6-3.0 mm wide, with 22-37 chaetigers. Anterior part of the body dorso-ventrally compressed, becoming distinctly narrower, almost cylindrical in cross section from around chaetiger 14-20. All specimens had lost their palps. Notopodial lamellae completely fused with branchiae from chaetiger 2 to 12-29 (usually from chaetiger 2 to 29), lamellae with ruffled margin. Small specimens with low dorsal crests from chaetiger 3 to the end the body; larger specimens only with low dorsal folds or tenuous folds (ECOSUR-000). Neuropodial hooded hooks from chaetiger 16-25 (usually chaetiger 19), numbering seven-nine per fascicle, hooks with three pairs of apical teeth. Pygidium lost in almost all specimens; two specimens (ECOSUR-000) have pygidium with large, broad ventral cushion. (Fig. 9D)

Distribution. U.S. Atlantic coast, New England to North Carolina; Gulf of Mexico; Central California; Japan. This is a wide distribution which requires a detailed study to confirm if these specimens really belong to the same morphological species.

Acknowledgements

I thank Vivianne Solís-Weiss and Alejandro Granados-Barba (LECyP-ICML-UNAM), México, Nancy Voss (UMML), Mark Siddall (AMNH) for making their materials available. I also thank Nancy Voss and Héctor Reyes (RSMAS) for providing laboratory space and housing facilities. Sergio I. Salazar-Vallejo and Vasily I. Radashevsky provided advice during the course of this study, and critically reviewed the manuscript. Many thanks also to Danny Eibye-Jacobsen (ZMUC) and one anonymous reviewer for critically revising this manuscript. I also thank Guadalupe Nieto (ECOSUR) for her help with the SEM pictures. During this study I enjoyed a scholarship from the Consejo Nacional de Ciencia y Tecnología (CONACyT) in El Colegio de la Frontera Sur, Chetumal (México) and generously supported by the Universidad de Quintana Roo and the Secretaría de Educación Pública (SEP-PROMEP).

References

Blake JA. 1996. Family Spionidae Grube, 1850, including a review of the genera and species from California and a revision of the genus Polydora Bosc, 1802; pp 81-223. In: Taxonomic Atlas of the Benthic Fauna of the Santa Maria Basin and the Western Santa Barbara Channel. Vol. 6 The Annelida, Part 3. Polychaeta: Orbiniidae to Cossuridae. Blake JA, B Hilbig and PH Scott (eds), Santa Barbara Museum Nat. Hist., Santa Barbara.

Verrill AE. 1873. Report upon the invertebrate animals of Vineyard Sound and the adjacent waters, with an account of the physical characters of the region. Report of the United States Fisheries Commission for 1871-1872: 295-778.

Webster HE. 1879. Annelida Chaetopoda of New Jersey. Annual Report of the New York State Museum 32: 101-128.